The present invention relates to an aromatic polyester having the following structural units (1) to (5) and a molded article using the aromatic polyester. ##STR2##
wherein Ra, Rb, Rc, Rd, Re and Rf each independently represents a lower alkyl group, lower alkoxy group, phenoxy group, phenyl group or halogen atom, and n represents an integer from 0 to 3.
Conventionally, aromatic polyesters having the above-described structural units (1), (2), (3), (4) and (5) have been known. Particularly, aromatic polyesters which contain industrially easily available structural unit (2) more than diol structural unit (3) are proposed. For example, aromatic polyesters have been proposed in which the ratio of (2)/(3) (=molar ratio of (2) to (3), that is, ratio of number of unit (2) to number of unit (3) in the aromatic polyester. Hereinafter in this specification, each (1), (2), (3), (4) and (5) sometimes refer the structural units (1), (2), (3), (4) and (5), respectively, and the molar ratio of a unit to another unit is indicated by using b "/".) is 1 or more and 12 or smaller, and (4)/(5) is 0 or more and 1 and smaller (Hereinafter, this aromatic polyester is referred to as "Polyester I".). Specifically, an aromatic polyester in which (2)1/(3) is 5.00 and (4)/(5) is 0.31 Is disclosed(JP-A-60-38425).
Besides this, as aromatic polyesters having more improved molding property than Polyester I, those in which the ratio of (4)/(5) is 1.04 or more and 19 or smaller, and (2)/(3) is 0.1 or more and 2.67 and smaller has been proposed (Hereinafter, this aromatic polyester is referred to as "Polyester II".). Specifically, an aromatic polyester in which (2)/(3) is 1.00 and (4)/(5) is 2.33 is disclosed(JP-A-63-57633).
In recent years, since aromatic polyesters are used for electric and electronic components, those which give molded articles having excellent solder temperature resistance and rigidity(flexural elastic modulus) are demanded. However, there are problems that molded articles made from Polyester I exhibit low solder temperature resistance, and Polyester II exhibit low rigidity.